Control valve assembly for a deck elevator engine having wave action compensation



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CHARLES E. GREGORY [AT TQ PNE c. E. GREGORY CONTROVL VALVE'ASSEMBLY FOR A DECK ELEVATOR ENGINE Sept. 15,l 1970 HAVING WAVE ACTION COMPENSATION 5 Sheets-Sheet Filed Feb. 5. 1968 INVENTOR. CHAP/ Es E', vGREGORY m hmm.

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.'GREGCRY Y Fon` A DECK lNINEVATOR EN HAVING WAVE ACTION COMPENSATION Sept. 15, 1970 coNTRoL VALVE AssE ,sfsheets-shepr-f Filed Feb. s; 196e INVENTOR CHARLES E GREGORY ATTQPNE; Ys

United States Patent CONTROL VALVE ASSEMBLY FOR A DECK ELEVATOR ENGINE HAVING WAVE ACTION COMPENSATION Charles E. Gregory, Anchorville, Mich., assignor to Jered Industries, Inc., Birmingham, Mich., a corporation of Michigan Filed Feb. 5, 1968, Ser. No. 702,887 Int. Cl. B66b 1]/04 U.S. Cl. 187-26 8 Claims ABSTRACT OF THE DISCLOSURE This specification describes a control valve assembly for controlling changes in pressure in a hydrostatic engine for operating a ships deck edge elevator. The engine includes a pressure movable piston which is connected through a cable and sheave assembly to a vertically movable elevator platform, and pressure is exhausted from the cylinder as the elevator is lowered under its own weight. The valve assembly modifies pressure variations in the working cylinder of the engine as the elevator is subjected to impact forces caused by wave action.

GENERAL DESCRIPTION OF THE INVENTION The improvements of my invention may be applied to deck elevators which operate between deck levels in a naval aircraft carrier vessel, but it is capable also of other uses. It is known practice to provide aircraft carrier elevators at the forward-port ight deck location and the aft-starboard flight deck location. The elevators are located at the flight deck edge, and they may be used to carry aircraft, as well as .maintenance equipment and other cargo, between a lower deck location and the upper flight deck location. The elevator is mounted in cantilever fashion in guide rails extending vertically adjacent the ships shell with the elevator platform extending in parallel disposition with respect to the water surface. The elevator is raised and lowered by means of a cable and sheave arrangement which is actuated by a hydraulic engine. By preference, the engine is located below the main deck.

The engine includes a fixed cylinder within which is assembled a pressure operated piston. The piston is connected by means of a piston rod to a movable sheave assembly that forms a part of the cable and sheave connection between the engine and the elevator.

As uid pressure is admitted to the working chamber defined by the piston and cylinder, the piston moves in a direction that will cause upward vertical movement of the elevator. As fluid is exhausted from the cylinder, the elevator and the cargo it carries is lowered under its own static weight from the upper level to the lower level as the piston is retracted to its original position.

There is a tendency for elevators of this kind to be subjected to wave action7 especially when the elevator is positioned at its lowest deck level. As the elevator platform is impacted by a wave, the platform is driven vertically upward and the cables of the cable and sheave assembly tend to become slack. This immediately relieves the load on the piston, thereby immediately tending to cause the working pressure to be reduced to a zero value. When the impact of the wave has subsided, it will be followed by a tendency for the elevator platform to fall as a free falling mass. At that instant there is no restraining influence provided by the slack cables. The elevator, after the slack has been taken up, will come to an abrupt halt thereby imposing severe dynamic loads on the cables, and causing cable failure and damage to the cable and sheave assembly and the hydraulic engine as well as to the elevator platform itself.

It is an object of my invention to overcome the problems associated with such impact loading of the elevator platform by counteracting the tendency of the working pressure acting in the hydraulic engine to fall to a Zero value as the elevator is raised by the impact forces of the wave action. My invention includes an air cylinder which acts as a pressure accumulator for maintaining sufficient pressure on the working piston of the hydraulic motor to avoid development of a slack condition in the cable and sheave assembly. After the wave action has subsided, the weight of the elevator and its load again will result in a restoration of the working pressure in the hydraulic motor, thereby avoiding free falling of the elevator platform. The valve assembly of my invention is capable further of allowing the elevator to creep back to its original position with a cushioned action.

BRIEF DESCRIPTION OF THE FIGURES IN THE DRAWINGS FIG. l shows a partial transverse sectional view of a naval aircraft carrier vessel showing the forward-port deck edge elevator in which the improvements of my invention are `adapted to be used.

FIG. 1A is a View similar to FIG. 1 although it shows the elevator in a stowed position.

FIG. 2 shows a plan view of the main deck for the carrier vessel in FIG. 1 and FIG. 1A.

FIGS. 3 and 3a are schematic circuit diagrams showing hydraulic pressure distribution conduits for the hydraulic engine used to raise and lower the elevator of FIGS. 1 and 1A.

FIG. 4 is a partial cross `sectional view of the hydraulic engine used to raise and lower the deck elevator.

FIG. 5 is a cross sectional view of the wave compensating valve assembly used with the hydraulic engine of FIG. 4.

PARTICULAR DESCRIPTION OF THE INVENTION In FIG. l the inner port-side bulkhead for an aircraft carrier is identified generally by reference character 10. This view is a schematic line diagram showing the relationship of an elevator platform 12 to the shell of the ship, the latter being generally indicated by reference character 14.

The main deck, which is the lowest operating station for the platform 12, is indicated at 16. The flight deck, which is the lowest deck of the ship, is shown at 22. This at 18.

A second deck, which forms the base for the elevator machinery, is indicated in FIG. 1 at 20. A third deck, which is the lowest deck of the ship, is shown at 22. This deck forms a support for the pressure tank, control fluid storage tank, the sump pump and the main control pump and motor as well as other ships machinery.

A gallery deck 24 can be situated directly below the flight deck 18. It supports the overhead sheaves 26 for the elevator assembly, as well as certain control elements of the hydrostatic engine and sheave assembly that control the vertical motion of the elevator platform. Other control elements can be mounted on the main deck, as indicated at 28.

The hydrostatic engine and sheave assembly is mounted on the second deck below the main deck level. A plan view of the elevator engine can best be seen by referring to FIG. 2 where the engine is shown in phantom lines. Reference may be had to Pat. No. 3,347,525 for a more complete disclosure of the elevator engine and sheave assembly. That patent is assigned to the assignee of my present invention.

In FIG. 2 the elevator engine is indicated at 28 and is mounted with the axis of the elevator engine cylinder in a horizontal position with respect to the second deck. A sheave is secured to the second deck 20, as described in the aforesaid patent, and elevator operating cables 32 are trained over the sheave. The lower ends of the cables 32 are connected to the piston of the hydrostatic engine 28. The engine itself is secured to a base plate carried by the second deck, and the engine piston moves in a plane parallel to the second deck as it applies tension to the cables 32.

The cables 32 extend vertically upward through the main deck 16, and they are enclosed by a cable trunk 34. The cables are trained over the overhead sheaves 26 and are extended in a horizontal direction to the sheaves 36.

The cables extend downwardly after being trained over the sheaves 36 and are tied to cable hitches 38 on the elevator platform assembly.

The platform assembly 12 includes an upper elevator deck 40 and structural members 42 and 44. The platform assembly is arranged in cantilever fashion, and guide rollers 46 and 48 are joined to the inboard end thereof, as shown best in FIG. 1. The guide rollers as assembled in registry with a guide rail 50, which is secured in vertical fashion to the -bulkhead 10. As the cables 32 are tensioned by the hydrostatic engine 28, they raise the platform assembly 12 from the lower position, indicated in FIG. 1 by solid lines, to the upper position, shown in FIG. 1 by dotted lines. At the lower position the platform deck 40 is aligned with the main deck 16. At the upper position the deck 40 is aligned with the flight deck 18.

As seen in FIG. 1A, the platform assembly 12 is hinged for angular adjustment about the axis 52 so that it can assume a stowed position, When the platform is lowered to the position shown in FIG. l, a reaction member 54 engages an anchor member 56 which is secured in fixed fashion to the structural elements that are secured to the guide rollers 46 and 48. These elements are identified in FIG. 1A by reference character 58'. A life net 60 at the extended end of the cantilever structure of platform assembly 12 can be moved so that it assumes the position shown in FIG. 1A when the platform assembly 12 is in the stowed position. When the platform assembly is extended, it assumes the position of FIG. 1.

The main pumps and rotors for pressurizing the elevator engine are located at the third deck level, as indicated in FIG. 1 at 62. Similarly, the pressure tank, the exhaust tank and the storage tank are located at the third deck level, as indicated in phantom lines by reference character 64, 66 and 68 in FIG. 2.

The bulkhead for the ship has an opening to form a passageway between the main deck area and the storage area on the platform. This passageway can be closed by sliding doors 70 which are supported by the main deck and which can be moved in a fore and aft direction.

The elevator platform assembly moves from the upper position to the lower position under its own weight. It is moved from the lower position to the upper position as the cables are drawn in tension by the elevator engine. If the elevator assumes the lower position as shown in FIG. 1, it is susceptible to wave action. When it is impacted by a wave, it will tend to rise and the guide rollers will move vertically along the guide rail 50. After the wave impact has subsided, a tendency will exist for the elevator platform assembly to fall under its own weight. If the cable at that time is slack, the elevator will fall until the slack is removed from the cable, at which time the elevator will come to an abrupt halt thereby stressing the cable with an impact load that is considerably higher than the normal static loads to which the cable would be subjected due to the weight of the platform and the cargo it carries. This tends to overstress the sheave supporting structure and the engine itself. The improvement of my invention tends to eliminate this shock loading due to wave action.

In FIG. 3 I have shown in schematic form the control pressure circuitry for actuating the elevator engine as it raises and lowers the elevator platform assembly. The hydrostatic engine itself is designated by numeral 28. It includes a cylinder 72 and a piston 74. The cylinder and the piston cooperate to define a pressure chamber or working chamber 76. A piston rod 78 extends from the piston 74, and one of the operating sheaves of the elevator engine is connected to the rod 80.

The space on the right hand side of the piston 74 within the cylinder 72 is in communication with the ambient air through an air passage 82. An air filter 84 communicating with the passage 82 filters the air that is admitted to the cylinder 72 as the piston 74 moves in a left hand direction upon lowering of the elevator platform assembly.

-High pressure is distributed to a pressure control valve assembly 86 through a pressure feed passage 88. This passage communicates with a high pressure line 90. A positive displacement variable capacity pump 92, which is powered by a drive motor 94, has its outlet passage in communication with supply passage 90 through one Way flow valve `96. A pressure regulator valve 98, which communicates with the discharge side of the pump 92, develops a controlled pressure in the inlet side of the pump as indicated at 100. When the pressure exceeds a calibrated value, the control cylinder 102 for the pump 92 is actuated so that the pump 92 will assume a displacement that will be sufficient to maintain the desired calibrated pressure in passage 90.

Other pump and motor combinations for supplying control pressure to passage 90 are shown at 104 and 106. These are situated in parallel relationship with respect to the pump and motor assembly shown at 92 and 94. Two piston accumulators 108 and 110 are in uid communication with passage 90 through passage 112. This passage 112 communicates with each of the accumulator pressure chambers shown at 114 and 116 through appropriate valve structure. A storage ask 118 for the accumulatore fluid communicates with the accumulator cylinders on the side of the pistons opposite to the chambers 114 and 116. The pistons are indicated by reference characters 120 and 122. The ask 118 is pressurized with ships air thereby applying a supercharge pressure to the accumulators.

An exhaust conduit 124 communicates with the exhaust side of the control valve assembly 86. When the control valve spool shown in part at 126 is shifted in a left hand direction, high pressure is admitted from passage 88 to the left hand side of the piston 74 thereby causing the sheave assembly to raise the platform. When the valve spool 126 is moved in a left hand direction, the working chamber 76 behind the piston 74 is opened to the exhaust conduit 124. As pressure distribution from the passage 88 is interrupted, passage 124 communicates directly with the exhaust tank 128. This is pressurized with the ships air to establish a reduced exhaust fluid pressure for supplying make-up uid for the accumulators 108, 110, as well as the supercharge pressure for the pump 92 and its companion pumps generally shown at 104 and 106.

The working chamber 76 on the left hand side of the piston 74 is in fluid communication with a pressure reservoir 130. This comprises a cylinder 132 in which is positioned a movable accumulator wall 134. The wall cooperates with cylinder 132 to define an air pressure chamber. This chamber, which is identified generally at 136, is in communication with an air pressure accumulator tank 138 through a normally open Valve 140i. The tank 138 is supplied with ships air through air supply passage 142.

The left hand side of the movable wall 134 is in fluid communication with the chamber 76 through a valve control passage 144. Pressure distribution from the chamber 76 to the accumulator pressure cylinder 132 takes place through restricted flow by-pass passage 146. Flow in the opposite direction from the cylinder 132 to the chamber 76 can occur rapidly, however, through oneway fiow valve 148.

When the elevator platform assembly is subjected to impact loading due to wave action, it will rise as described previously. This tends to produce a slack in the cables thereby relieving the load on the' piston 74 for the hydrostatic engine 28. This will result in a tendency for the pressure in the chamber 76 to immediately fall to a value of zero. As the pressure in the chamber 76 falls, valve 148 will open immediately because of the pressure behind the movable accumulator wall .134. Fluid under reduced air pressure is admitted then to the chamber 76 thereby causing a minimum load on the piston 74 that will be sufficient to maintain the cables taut and avoid the development of a slack condition. When the wave action has subsided, the cables again will be tensioned and the pressure in the chamber 76 immediately will be restored. At that time the exhausted cylinder 132 will again be charged because of the bleeding action across the valve 148 through the by-pass passage 146. Thus, the pressure accumulator 132 again will be conditioned for a subsequent supercharge during the next impact loading of the platform if the wave action continues.

In FIG. 4 I have shown in cross sectional form the working cylinder of the hydrostatic engine and a portion of the pressure accumulator 132. The cylinder for the hydrostatic engine 28 is defined by a cylinder housing 150 in which the piston 74 is slidably situated. The right hand end of the cylinder 72 is closed by closure plate 74'. This is apertured to provide communication with an ambient pressure passage 152, the intake end of which communicates with air filter 154. Air displaced from the right hand side of the piston 74 as the elevator is raised is discharged through the passage 152. The same passage provides replacement air as the elevator is lowered and the the piston moves in a left hand direction.

The left hand end of the housing 150 is closed by domeshaped closure member 156. A seal housing 158 is joined to the member .156 and is provided with a central shaft opening 160 for receiving piston rod 78.

The pressure reservoir 130 is joined to and is `supported by the housing 150, suitable supporting brackets 162 being provided for that purpose. The left hand end of the reservoir 130 is joined to supporting end plate 1.64 through valve housing 166. The left hand side of the valve housing 166 communicates through the passage 144, which extends to a working chamber 76 of the hydrostatic engine.

Valve housing 166 encloses a movable valve plate 168 which is hinged at one side thereof, as shown at 170. It registers with valve seat .172 which surrounds one end of passage 174 extending to the interior of the reservoir 130. A flow restricting orifice 176 is formed in the valve plate 168 to provide a restricted fluid communication hetween the chamber 76 and the interior of the reservoir 130 during the portion of the operating cycle of the hydrostatic engine in which the chamber 76 is pressurized, orifice 176 will permit a charge pressure to be distributed to the reservoir 130 thereby maintaining the piston 74 in its loaded right hand position. This load is resisted by the air pressure that exists on the right hand side of the piston 134. This pressure, as explained earlier, is supplied by the precharged tank 138. The air thus acts as an air sprin-g to maintain a minimum charge pressure in the reservoir 130 which is sufiicient to maintain a taut condition at all times in the cable and sheave assembly. The residual pressure is suicient to allow the cable to remain taut when the elevator platform is driven upward by a wave. When the crest of the wave has passed, the elevator platform will be gently lowered as the working pressure in the engine is restored. The gentle lowering of the platform is due to the bleeding of fluid from cham- Iber 76 to the reservoir through orifice 176.

When the elevator is impacted by a wave and the slack condition in the cables tends to occur, the pressure in the chamber 76 immediately will fall. This will cause the valve plate 168 to open to establish free communication between the reservoir .130 and the chamber 76. This establishes a fiuid ow path that bypasses the orifice 176.

Having thus described a preferred form of my invention, what I claim and desire to secure by U.S. Letters Patent is:

1. In a hydrostatic elevator engine assembly adapted to raise and lower an elevator platform from one level to another level, a hydrostatic cylinder, a hydrostatic piston movably mounted in said cylinder and cooperating therewith to define a pressure chamber, a cable and sheave assembly including power sheaves connected to said piston, idler sheaves situated at spaced operating levels and an operating cable trained over said power sheaves and said idler sheaves and connected operatively to said elevator platform, a hydrostatic pressure source, conduit structure connecting said pressure chamber with said pressure source, a pressure reservoir, valve means situated in and partly defining said conduit structure for controlling distribution of pressure to said pressure chamber and for controlling exhausting of working pressure from said pressure chamber, said reservoir having a reservoir cylinder and a reservoir piston, a passage between said reservoir and said pressure chamber, and pressure sensitive valve means in said passage for establishing communication between said reservoir and said pressure chamber as the magnitude of the pressure in said pressure chamber falls whereby a minimum pressure is maintained in said cylinder.

2. The combination as set forth in claim 1 wherein said reservoir piston cooperates with said reservoir cylinder to define on one side of said reservoir piston a chamber, said reservoir chamber being situated on the other side of said reservoir piston, and means for pressurizing said air chamber with a controlled air pressure.

3. The combination as set forth in claim 1 wherein said valve means comprises a one-way flow check valve having a movable valve element and a valve seat, said valve seat defining in part said passage, said movable valve element being moved against its valve seat to close said passage when the pressure in said working chamber exceeds the pressure in said reservoir chamber, and a flow restricting orifice situated in parallel disposition with respect to said valve whereby restricted communication is maintained continuously between said reservoir chamber and said working chamber.

4. The combination as set forth in claim 2 wherein said valve means comprises a one-way flow check valve having a movable valve element and a valve seat, said valve seat defining in part said passage, said movable valve element being moved against its valve seat to close said passage when the pressure in said working chamber exceeds the pressure in said reservoir chamber, and a flow restricting orifice situated in parallel disposition with respect to said valve whereby restricted communication is maintained continuously between said reservoir chamber and said working chamber.

5. The combination as set forth in claim 1 wherein said piston for said hydrostatic engine is movable under the influence of pressure in said working chamber in one direction thereby raising said platform through said cable and sheave assembly, the weight of said platform returning said piston in the opposite direction as pressure is exhausted from said working chamber, the magnitude of the pressure in said working chamber being dependent upon the gravity load on said platform minus inertia forces on said platform due to impact loads.

6. The combination as set forth in claim 2 wherein said piston for said hydrostatic engine is movable under the infiuence of pressure in said working chamber in one direction thereby raising said platform through said cable and sheave assembly, the weight of said platform returning said piston in the opposite direction as pressure is exhausted from said working chamber, the magnitude of the pressure in said working chamber being dependent upon the gravity load on said platform minus inertia forces on said platform due to impact loads.

7. The combination as set forth in claim 3 wherein said piston for said hydrostatic engine is movable under the influence of pressure in said working chamber in one direction thereby raising said platform through said cable and sheave assembly, the weight of said platform returning said piston in the opposite direction as pressure is exhausted from said Working chamber, the magnitude of the pressure in said Working chamber being dependent upon the gravity load on said platform minus inertia forces on said platform due to impact loads.

8. The combination as set forth in claim 4 wherein said piston for said hydrostatic engine is movable under the inuence of pressure in said working chamber in one direction thereby raising said platform through said cable and sheave assembly, the weight of said platform re- References Cited UNITED STATES PATENTS 2,408,758 10/1946 Dunlop 254-175 2,955,897 10/1960 Noe 60-51 3,163,005 12/1964 Reed 60-51 3,314,657 4/1967 PeudHomme 254--189 3,347,525 10/ 1967 Gregory 187-26 HARVEY C. H'ORNSBY, Primary Examiner U.S. Cl. X.R.

[mman STATES PATENT OFFICE (II`,I{'I`II`I(1A'I`|`. 0F CORRECTION Patent No. 3 528 527 Dated Septembr' l5, 1970 Charles E. Gregory Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent: are hereby corrected as shown below:

Column 2, line 48, "lowest deck of the ship, is shown at 22. This" should be uppermost operating station, is indicated (For reference, see application specification page 5, lines 8 and 9.)

Column 4, line 74, after "through" insert a (For reference, see application specification page 10, line l.)

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